File device and file access method

a file device and file access technology, applied in the field of file device and file access method, can solve the problems of invalid data sequence in the added storage, inability to read out the entire data recording sequence on the storage medium, and the existence of a storage medium capable of storing data, etc., and achieve the effect of effective us

Inactive Publication Date: 2008-04-22
FUJITSU LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0045]According to the present invention, by halting readout of a file and updating the management information so that subsequent blocks become unused blocks when information indicating the preceding block does not indicate the preceding block as a result of the block being accessed in sequence depending on the management information, the file being read out, and data being read out from the block, or when information indicating the size of the data recorded in the block is outside the actual block size range, it is possible to stop the readout of incorrect data and it is possible to update the management information so that the stored blocks of incorrect data become unused blocks. As a result, blocks can be used by other files and effective use can be made of the unrecorded blocks.

Problems solved by technology

When accessing the file, if the management information stored in the external storage device and the data sequence have been accessed alternately, a seek to the external storage device occurs for each access, which is inefficient.
However, in such a system, when recording data in the external storage device, in the event of a forced termination of the system, a system shutdown due to a power failure, or forced ejection of the removable storage medium when the external storage device is of the removal storage medium type and so forth, the management information that has been temporarily stored in the buffer is not recorded in the external storage device.
When the management information is not recorded in the external storage device and the file is accessed after restoration from any of the above-mentioned interruptions, because the management information has not been recorded a problem occurs in that the entire data recorded on the storage medium sequence cannot be read out.
It should be noted that if management information for the data sequence in the added storage cannot be stored due to a failure, then the data sequence in the added storage becomes invalid and a recovery process is carried out using the preceding data sequence.
However, according to the conventional USP method of (1), the existence of a storage medium capable of storing data even during a failure is required, and suffers the disadvantage of being unable to cope when removable media are forcibly removed.
If the blocks have been stored randomly, however, then a seek occurs each time an individual block is accessed, creating the problem of necessitating processing time.
As a result, random access occurs and disk access efficiency decreases.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

first embodiment

[0060]FIG. 3 is a block diagram of the present invention.

[0061]The file device 100 of the present invention is composed of a host computer 101 and an external storage device 102.

[0062]The host computer 101 comprises a CPU 103, ROM 104, RAM 105 and an input / output interface 106 all connected by a bus 107, and controls the external storage device 102.

[0063]The CPU 103 performs all manner of controls using applications stored in the ROM 104. The RAM 105 is used as the work memory of the CPU 103.

[0064]The file system 108 of the present embodiment is achieved by the applications stored in the ROM. The applications that achieve the file system 108 are opened by the RAM 105 during execution and are executed by the CPU 103.

[0065]The file system 108, as its function block, is composed of an access processor 109, a block allocation unit 110, a management information integration unit 111 and a management information storage unit 112. The access processor 109 controls the writing of data to the...

second embodiment

[0133]FIG. 12 is a diagram illustrating a scheduling of the present invention.

[0134]As shown in FIG. 12(A), the video image B has an encoding rate that is twice that of video image A and video image C and the number of blocks transferred at time of access to the external storage device 102 is the same. Additionally, video images A, B and C are assumed to have the same degree of priority.

[0135]The recording of video images A, B and C according to the results of the scheduling involves, as shown in FIG. 12(B), recording video image A over blocks after recording video image B over 4 blocks, and further, recording video image C over 4 blocks after recording video image B over 4 blocks. This process is continued until the recording of each video image is completed. Additional scheduling is conducted in the event that conditions change during recording, such as the number of channels increases or decreases.

[0136]Next, the allocation of blocks is carried out based on the scheduling informa...

third embodiment

[0143]FIG. 14 is a diagram illustrating an operation of the present invention.

[0144]It should be noted that the composition of the present embodiment is the same as that of FIG. 11, so a description thereof is omitted.

[0145]Additionally, the scheduling is also the same as the scheduling of the second embodiment shown in FIG. 12, so a description thereof is omitted.

[0146]As shown in FIG. 14, the latest management information is recorded in the management information recorded in the management information storage unit 112 set in the RAM 105 of the host computer 101.

[0147]By contrast, in the external storage device 102 is recorded the management information 113 previously stored from the management information storage unit 112 to the external storage device 102. When storing individual video images according to the scheduling, first the storage area for the video image scheduled first is retained.

[0148]At this time, first, an unallocated region is sought using the block allocation info...

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Abstract

The present invention relates to a file device and file access method that divides a file into units of clusters or blocks and records, and has as its object to provide a file device and file access method such that even when there is a failure and the data is not recorded correctly to the end the data that has been recorded can be accessed. When recording a file to an external storage device divided among a plurality of blocks, the blocks that are to record the file are pre-allocated in the external storage device, management information that indicates the allocated blocks is created and the management information is recorded in the external storage device, after which the data that makes up the file is recorded in the external storage device.

Description

[0001]This application is a continuing application filed under 35 U.S.C. § 111(a), based upon International Application PCT / JP99 / 04711, filed Aug. 31, 1999.TECHNICAL FIELD[0002]The present invention relates to a file device and file access method, and more particularly, to a file device and file access method that divides a file into units of clusters, blocks, or the like for recording and management.BACKGROUND ART[0003]Conventionally, OS (operating systems) such as MS-Windows and UNIX, when storing data to an external storage device, have stored connections of individual clusters, blocks or the like in management data called an FAT (File Allocation Table) and an index node (i-node).[0004]In such a system, when a file is read out, the clusters or blocks corresponding to that file are accessed in sequence while referring to the management information.[0005]Additionally, when storing a new file or when rewriting data, conventionally, clusters or blocks for storing the new data sequenc...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): G06F17/00G06F3/06G06F11/00G06F11/14G06F17/30G11B27/034G11B27/10G11B27/32
CPCG06F11/004G06F11/0727G06F11/1435G06F17/30067G11B27/034G11B27/105G11B27/329G11B2220/20G06F16/10
Inventor KARASUDANI, AKIRAOKADA, YOSHIYUKI
Owner FUJITSU LTD
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